TWI757622B - A wireless transmit receive unit and a method implemented thereby - Google Patents

Abstract

Systems, methods, and devices for efficient and robust handling of acknowledgements in new radio unlicensed bands (NR-U) environments. A wireless transmit receive unit (WTRU) may receive control information and a data transmission from a gNB in a first interval (i.e., transport block or channel occupancy time), wherein the control information may include an indication of uplink resources. The data transmission may require some sort of acknowledgement (i.e., HARQ feedback). The WTRU may attempt to transmit the acknowledgement in the indicated uplink resources, but the gNB may not receive the acknowledgement. The WTRU may receive control information and a data transmission from the gNB in a second interval, including an indication to aggregate any previously unsuccessful acknowledgement transmissions. The WTRU may transmit an aggregated acknowledgement including previous unsuccessful acknowledgements and any additional acknowledgements from the current interval. In some cases, look-before-talk procedures may be used.

Description

Wireless transmit/receive unit and method therefor priority claim

This application claims the benefit of US Provisional Application No. 62/716,211, filed August 8, 2018, and US Provisional Application No. 62/753,457, filed October 31, 2018, the contents of which are incorporated by reference here.

In the field of wireless communications, next-generation air-interfaces such as new radio can support a wide range of use cases for different spectrum usage models, such as licensed, unlicensed/shared, etc. In order to operate in a shared spectrum, systems, methods, and apparatuses that enable efficient and reliable wireless communication in unlicensed frequency bands may be required.

Systems, methods, and apparatus for efficient and robust processing of responses in a New Radio Unlicensed (NR-U) environment. A wireless transmit receive unit (WTRU) may receive control information and data transmissions from the gNB in a first interval (ie, transport block or channel hold time), where the control information may include an indication of uplink resources. Data transmission may require some kind of acknowledgement (ie HARQ feedback). WTRU An attempt may be made to transmit the acknowledgment in the indicated uplink resource, but the gNB may not receive the acknowledgment. The WTRU may receive control information and data transmissions from the gNB in the second interval, including an indication to aggregate any previously unsuccessful acknowledgement transmissions. The WTRU may transmit an aggregated acknowledgment from the current interval including the previous unsuccessful acknowledgment and any additional acknowledgments. In some cases, a look-before-talk procedure may be used.

100: Communication Systems

102, 102a, 102b, 102c, 102d: Wireless Transmit/Receive Units (WTRUs)

104/113: Radio Access Network (RAN)

106/115: Core Network (CN)

108: Public Switched Telephone Network (PSTN)

110: Internet

112: Other Networks

114a, 114b: base station

116: Air Media

118: Processor

120: Transceiver

122: transmit/receive element

124: Speaker/Microphone

126: Keypad

128: Monitor/Trackpad

130: Non-removable memory

132: removable memory

134: Power

136: Global Positioning System (GPS) Chipset

138: Peripherals

160a, 160b, 160c:e Node B

162: Mobility Management Entity (MME)

164: Service Gateway (SGW)

166; Packet Data Network (PDN) Gateway (or PGW)

180a, 180b, 180c: gNB (g Node B)

182a, 182b: Access and Mobility Management Function (AMF)

183a, 183b: Session Management Function (SMF)

184a, 184b: User Plane Function (UPF)

185a, 185b: Data Network (DN)

201, 301, 401, 501, 601, 701, 801, 1001: Time

810, 820, 910, 920: Channel Occupancy Time (COT)

1220, 1320: COT duration

1222, 1322: WTRU1 COT

1224, 1324: COT common part

CWp: contention window size

DAI: Downlink Assignment Indicator

EDAI: Enhanced Downlink Assignment Indicator

LBT: first listen and wait

N2, N3, N4, N6, N11, S1, X2, Xn: Interface

PDCCH: Entity Downlink Control Channel

PDSCH: Entity downlink shared channel

PUCCH: Physical Uplink Control Channel

TB: transport block

A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements in the drawings, and wherein: FIG. 1A illustrates that one or more of the disclosures may be implemented System diagram of an exemplary communication system of an embodiment; FIG. 1B is a system diagram illustrating an exemplary wireless transmit/receive unit (WTRU) that may be used in the communication system shown in FIG. 1A according to an embodiment; FIG. 1C Figure 1A is a system diagram illustrating an exemplary Radio Access Network (RAN) and an exemplary Core Network (CN) that may be used in the communication system illustrated in Figure 1A; Figure 1D is a diagram illustrating System diagram of another exemplary radio access network (RAN) and another exemplary core network (CN) that may be used in the communication system shown in FIG. 1A according to an embodiment; FIG. 2 is a WTRU not Figure 3 is an example transmission diagram where the WTRU fails to complete the LBT procedure; Figure 4 is an example transmission diagram where the WTRU has priority over the non-exclusive PUCCH; Figure 5 is an example transmission diagram where the WTRU succeeds An example transmission diagram of LBT completed but gNB failed to detect PUCCH; Figure 6 is an example transmission diagram of a WTRU preparing a HARQ codebook according to at least DAI and/or EDAI; Figure 7 is an example transmission diagram of a WTRU preparing a HARQ codebook according to at least DAI and/or EDAI; Figure 8 is an example transmission diagram of a WTRU based on Example transmission diagram for an EDAI aggregated HARQ codebook for one or more COTs; Figure 9 is an example transmission diagram where PUCCH resource assignments are outside the COT and using PUCCH from a later COT; Figure 10 is a WTRU check Figure 11 is an example transmission diagram for contention window adjustment; Figure 12 is an example transmission diagram for base COT sharing; and Figure 13 is a restricted hidden node Exemplary transmission diagram of affected COT sharing.

FIG. 1A is a diagram illustrating an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources including wireless bandwidth. For example, the communication system 100 may use one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA) ), single-carrier FDMA (SC-FDMA), zero-tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, and Filter Bank Multi-Carrier (FBMC), among others.

As shown in FIG. 1A, the communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104/113, CN 106/115, public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, however, it should be understood that any number of WTRUs, base stations, networks, and/or network elements are contemplated by the disclosed embodiments. Each WTRU 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. For example, WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as "stations" and/or "STAs") may be configured to transmit and/or receive wireless signals and may include user equipment (UE), mobile station, fixed or mobile subscriber unit, subscription-based unit, pager, mobile phone, personal digital assistant (PDA), smart phone, laptop, notebook, personal computer, wireless sensor detectors, hotspot or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical equipment and applications (such as remote surgery), industrial equipment and Applications (eg, robotics and/or other wireless devices operating in industrial and/or automated process chain environments), consumer electronic devices, and devices operating on commercial and/or industrial wireless networks, among others. Any of the WTRUs 102a, 102b, 102c, 102d may be referred to interchangeably as a WTRU/UE.

Communication system 100 may also include base station 114a and/or base station 114b. Each base station 114a, 114b may be configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate its access to one or more communication networks (eg CN 106/115, Internet 110, and/or other network 112) devices of any type. For example, base stations 114a, 114b may be base transceiver stations (BTS), Node Bs, eNodeBs, local NodeBs, local eNodeBs, gNBs, NR NodeBs, site controllers, access points (APs) ), and wireless routers, etc. Although every A base station 114a, 114b is described as a single element, however it should be understood that base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

The base station 114a may be part of the RAN 104/113, and the RAN 104/113 may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), radio network controller (RNC) ), relay nodes, etc. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies called cells (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a specific geographic area that is relatively fixed or may vary over time. Cells can be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, that is, one transceiver for each sector of the cell. In one embodiment, base station 114a may use multiple-input multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d via an air interface 116, which may be any suitable wireless communication link (eg, radio frequency (RF) , microwave, centimeter wave, micron wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104/113 may implement such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) The radio technology that can use Wideband CDMA (WCDMA) to establish the air mesoplane 115/116/117. WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink (DL) Packet Access (HSDPA) and/or High Speed UL Packet Access (HSUPA).

In an embodiment, base station 114a and WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTA-Advanced (LTE-A Pro) to create the air interface 116 .

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access, which may use NR to establish the air interface 116.

In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access techniques. For example, base station 114a and WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together (eg, using dual connectivity (DC) principles). Accordingly, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by various types of radio access techniques, and/or transmissions to/from various types of base stations (eg, eNBs and gNBs).

In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement, for example, IEEE 802.11 (ie, Wireless High Fidelity (WiFi)), IEEE 802.16 (Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Radio technologies such as Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

Base station 114b in Figure 1A may be a wireless router, local NodeB, local eNodeB, or access point, and may use any suitable RAT to facilitate, for example, business premises, residences, vehicles, campuses, industrial facilities, air corridors (e.g. for drones) and wireless connectivity in localized areas such as roads. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may use a cellular-based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish picocells or Femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b does not need to access the Internet 110 via the CN 106/115.

The RAN 104/113 may communicate with the CN 106/115, which may be configured to provide voice, data, applications and/or the Internet to one or more of the WTRUs 102a, 102b, 102c, 102d Any type of network for Voice over Protocol (VoIP) services. The data may have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. CN 106/115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and/or may perform advanced security functions such as user authentication. Although not shown in Figure 1A, it should be understood that RAN 104/113 and/or CN 106/115 may communicate directly or indirectly with other RANs using the same RAT as RAN 104/113, or a different RAT . For example, the CN 106/115 can communicate with another RAN (not shown) using GSM, UMTS, CDMA 2000, WiMAX, E-UTRA or WiFi radio technology in addition to connecting with RAN 104/113 using NR radio technology .

The CN 106/115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112. PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include communication protocols that use common communication protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and/or Internet Protocol (IP) in the TCP/IP family of Internet protocols. A global system of interconnected computer network devices. Network 112 may include wired and/or wireless communication networks owned and/or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may use the same RAT or a different RAT as the RANs 104/113.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multimode capabilities (eg, the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers that communicate over different wireless links with different wireless networks) . For example, the WTRU 102c shown in Figure 1A may be configured to communicate with a base station 114a, which may use a cellular-based radio technology, and with a base station 114b, which may use an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an exemplary WTRU 102 . 1B, the WTRU 102 may include a processor 118, transceiver 120, transmit/receive elements 122, speaker/microphone 124, keypad 126, display/trackpad 128, non-removable memory 130, removable Memory 132 , power supply 134 , global positioning system (GPS) chipset 136 and other peripherals 138 . It should be appreciated that the WTRU 102 may also include any subcombination of the foregoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller , Application-Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuits (ICs), and state machines, among others. The processor 118 may perform signal encoding, data processing, power control, input/output processing, and/or any other function that enables the WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120 , which may be coupled to transmit/receive element 122 . Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may also be integrated in one electronic component or die.

Transmit/receive element 122 may be configured to transmit signals to and receive signals from base stations (eg, base station 114a ) via air interposer 116 . For example, in one embodiment, transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. For example, in another embodiment, transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive RF and optical signals. It should be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as a single element, the WTRU 102 may include any number of transmit/receive elements 122 . More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (eg, multiple antennas) that transmit and receive radio signals via the air interface 116 .

Transceiver 120 may be configured to modulate signals to be transmitted by transmit/receive element 122 and to demodulate signals received by transmit/receive element 122 . As mentioned above, the WTRU 102 may have multimode capability. Accordingly, the transceiver 120 may include multiple transceivers that enable the WTRU 102 to communicate via various RATs (eg, NR and IEEE 802.11).

The processor 118 of the WTRU 102 may be coupled to a speaker/microphone 124, a keypad 126, and/or a display/trackpad 128 (eg, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may Receive user input from these components. Processor 118 may also output user data to speaker/microphone 124 , keypad 126 and/or display/touchpad 128 . Additionally, processor 118 may access information from, and store data in, any suitable memory, such as non-removable memory 130 and/or removable memory 132. The non-removable memory 130 may include random access memory (RAM), read only memory (ROM), hard disk, or any other type of memory storage device. Removable memory 132 may include a Subscriber Identity Module (SIM) card, memory stick, secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data to, memory that is not physically located in the WTRU 102, for example, such memory may be located on a server or home computer (not shown) .

The processor 118 may receive power from the power source 134 and may be configured to distribute and/or control power for other elements in the WTRU 102 . The power supply 134 may be any suitable device for powering the WTRU 102 . For example, power source 134 may include one or more dry battery packs (eg, nickel-cadmium (Ni-Cd), nickel-zinc (Ni-Zn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, and fuel cells, etc.

The processor 118 may also be coupled to a GPS chipset 136 that may be configured to provide location information (eg, longitude and latitude) related to the current location of the WTRU 102 . as In addition to or in lieu of information from GPS chipset 136, WTRU 102 may receive location information from base stations (eg, base stations 114a, 114b) via air interface 116, and/or from two or more nearby base stations based on signal timing to determine its position. It should be appreciated that the WTRU 102 may use any suitable positioning method to obtain location information while remaining consistent with the embodiments.

The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and/or hardware modules that provide additional features, functionality, and/or wired or wireless connectivity. For example, peripherals 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (for photos and/or video), universal serial bus (USB) ports, vibration devices, television transceivers, hands-free headsets, Bluetooth ® modules, frequency modulation (FM) radio units, digital music players, media players, video game console modules, Internet browsers, virtual reality and/or augmented reality (VR/AR) devices, and activity tracking device and so on. Peripherals 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors sensors, temperature sensors, time sensors, geolocation sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors and/or or humidity sensor.

The WTRU 102 may include a full-duplex radio for which some or all signals (eg, associated with particular subframes for UL (eg, for transmission) and downlink (eg, for reception)) The reception or transmission can be parallel and/or simultaneous. A full-duplex radio may include signal processing via hardware (eg, choke coils) or via a processor (eg, a separate processor (not shown) or via processor 118 ) to reduce and/or substantially eliminate self Interference management unit 139 for interference. In one embodiment, the WTRU 102 may include transmitting and receiving some or all of the signals A half-duplex radio (eg, associated with a particular subframe for UL (eg, for transmission) or downlink (eg, for reception)).

Figure 1C is a system diagram illustrating the RAN 104 and CN 106 according to one embodiment. As described above, the RAN 104 may use the E-UTRA radio technology over the air interface 116 to communicate with the WTRUs 102a, 102b, 102c. The RAN 104 may also communicate with the CN 106 .

The RAN 104 may include eNodeBs 160a, 160b, 160c, however it should be appreciated that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. Each eNodeB 160a, 160b, 160c may include one or more transceivers that communicate with the WTRUs 102a, 102b, 102c via the air interposer 116. In one embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO techniques. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each eNodeB 160a, 160b, 160c may be associated with a particular cell (not shown), and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and/or DL, and the like. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c can communicate with each other via the X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162 , a serving gateway (SGW) 164 , and a packet data network (PDN) gateway (or PGW) 166 . While each of the foregoing elements are described as being part of CN 106, it should be understood that any of these elements may be owned and/or operated by entities other than the CN operator.

The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via the S1 interface and may act as a control node. For example, the MME 142 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, performing bearer activation/deactivation, and at the WTRU 102a, 102b, 102c A particular service gateway is selected during the initial connection of 102b, 102c, and so on. MME 162 may also provide control plane functionality for handover between RAN 104 and other RANs (not shown) using other radio technologies (eg, GSM and/or WCDMA).

The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions such as anchoring the user plane during inter-eNodeB handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context, etc.

SGW 164 may be connected to PGW 166, which may provide WTRUs 102a, 102b, 102c with access to a packet-switched network (eg, Internet 110) to facilitate communication between WTRUs 102a, 102b, 102c and IP-enabled devices Communication.

CN 106 may facilitate communication with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network (eg, the PSTN 108) to facilitate communications between the WTRUs 102a, 102b, 102c and conventional landline communication devices. For example, CN 106 may include, or communicate with, an IP gateway (eg, an IP Multimedia Subsystem (IMS) server) that may act as an interface between CN 106 and PSTN 108 . Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers.

Although a WTRU is depicted as a wireless terminal in Figures 1A-1D, it should be appreciated that in some exemplary embodiments such a terminal uses a (eg, temporary or permanent) wired communication interface with a communication network .

In a typical embodiment, the other network 112 may be a WLAN.

A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may access or interface to a Distributed System (DS) or another type of wired/wireless network that carries traffic to and/or from the BSS. Traffic originating outside the BSS and destined for the STA may arrive via the AP and be delivered to the STA. Traffic originating from the STA and to destinations outside the BSS may be sent to the AP for delivery to the respective destinations. Traffic between STAs within the BSS may be sent via the AP, eg, the source STA may send the traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and/or referred to as point-to-point traffic. The point-to-point traffic may be sent between the source and destination STAs (eg, directly therebetween) using direct link setup (DLS). In some exemplary embodiments, the DLS may use 802.11e DLS or 802.11z Channelized DLS (TDLS). A WLAN using the Independent BSS (IBSS) mode may have no APs, and STAs (eg, all STAs) within the IBSS or using the IBSS may communicate directly with each other. Here, the IBSS communication mode may sometimes be referred to as an "ad-hc" communication mode.

When using the 802.11ac infrastructure mode of operation or a similar mode of operation, the AP may transmit beacons on a fixed channel (eg, the primary channel). The main channel can have a fixed width (eg, a 20MHz bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STA to establish a connection with the AP. In some typical embodiments, (eg, in 802.11 systems) Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented. For CSMA/CA, the STA (eg, each STA) including the AP can sense the primary channel. If a particular STA senses/detects and/or determines that the primary channel is busy, the particular STA may back off. In a given BSS, one STA (eg, only one station) may transmit at any given time.

High Throughput (HT) STAs may use 40 MHz wide channels for communication (eg, by combining a 20 MHz wide primary channel with a 20 MHz wide adjacent or non-adjacent channel to form a 40 MHz wide channel).

Very high throughput (VHT) STAs can support 20MHz, 40MHz, 80MHz and/or 160MHz wide channels. 40MHz and/or 80MHz channels can be formed by combining consecutive 20MHz channels. A 160MHz channel can be formed by combining 8 consecutive 20MHz channels or by combining two non-contiguous 80MHz channels (this combination may be referred to as an 80+80 configuration). For an 80+80 configuration, after channel encoding, the material can be passed through a segment parser, which can split the material into two streams. Inverse Fast Fourier Transform (IFFT) processing as well as time domain processing can be performed independently on each stream. The stream can be mapped on two 80MHz channels and the data can be transmitted by a transmitting STA. At the receiver of a receiving STA, the above operations for the 80+80 configuration can be reversed and the combined data can be sent to the medium access control (MAC).

802.11af and 802.11ah support sub-1GHz mode of operation. The channel operating bandwidth and carrier used in 802.11af and 802.11ah are reduced compared to the channel operating bandwidth and carrier of 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz and 20MHz bandwidths in TV white space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz and 16MHz bandwidths using non-TVWS spectrum. According to typical embodiments, 802.11ah may support meter type control/machine type communications (eg, MTC devices in macro coverage areas). The MTC may have certain capabilities, such as limited capabilities including support (eg, support only) of certain and/or limited bandwidths. The MTC device may include a battery with a battery life above a critical value (eg, to maintain a long battery life).

WLAN systems that can support multiple channels and channel bandwidths (eg, 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designated as the primary channel. The bandwidth of the primary channel may be equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by STAs of all STAs operating in the BSS supporting the minimum bandwidth mode of operation. In the case of 802.11ah, even though APs and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz and/or other channel bandwidth operation modes, the STAs that support (eg only support) 1MHz mode (eg MTC type device), the main channel can be 1MHz wide. Carrier sense and/or network allocation vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy (eg, because STAs (which only support 1 MHz mode of operation) transmit to the AP), the entire available frequency band may be considered busy even though most of the frequency band remains free and available.

In the US, the available frequency bands for 802.11ah are from 902MHz to 928MHz. In Korea, the available frequency band is from 917.5MHz to 923.5MHz. In Japan, the available frequency band is from 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah is from 6MHz to 26MHz.

Figure ID is a system diagram illustrating the RAN 113 and CN 115 according to one embodiment. As described above, the RAN 113 may communicate with the WTRUs 102a, 102b, 102c via the air interposer 116 using NR radio technology. The RAN 113 may also communicate with the CN 115 .

The RAN 113 may include gNBs 180a, 180b, 180c, but it should be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. Each gNB 180a , 180b , 180c may include one or more transceivers to communicate with the WTRUs 102a , 102b , 102c via the air interposer 116 . In one embodiment, gNBs 180a, 180b, 180c may implement MIMO techniques. For example, gNBs 180a, 180b may use beamforming to transmit to gNBs 180a, 180b, 180c Signal and/or receive signals from gNBs 180a, 180b, 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit wireless signals to and/or receive wireless signals from the WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, gNB 180a may transmit multiple component carriers (not shown) to WTRU 102a. A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multipoint (CoMP) techniques. For example, WTRU 102a may receive cooperative transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

The WTRUs 102a, 102b, 102c may use transmissions associated with a scalable set of parameters (numerology) to communicate with the gNBs 180a, 180b, 180c. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may be different for different transmissions, different cells, and/or different wireless transmission spectrum portions. The WTRUs 102a, 102b, 102c may use subframes or transmission time intervals (TTIs) of different or scalable lengths (eg, including different numbers of OFDM symbols and/or varying absolute time lengths) to communicate with the gNBs 180a, 180b , 180c to communicate.

The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in standalone and/or non-standalone configurations. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without access to other RANs (eg, eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as action anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may use signals in the unlicensed band to communicate with the gNBs 180a, 180b, 180c. In a non-standalone configuration, WTRUs 102a, 102b, 102c may communicate/connect with gNBs 180a, 180b, 180c at the same time as communicating/connecting with another RAN (eg, eNodeB 160a, 160b, 160c). For example, WTRUs 102a, 102b, 102c may implement DC principles substantially simultaneously with One or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c communicate. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as action anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and/or traffic to serve the WTRUs 102a, 102a, 102b, 102c.

Each gNB 180a, 180b, 180c may be associated with a particular cell (not shown), and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and/or DL, support network interception split, implement dual connectivity, implement interworking between NR and E-UTRA, route user plane data to user plane functions (UPF) 184a, 184b, and route control plane information to access and mobility management functions (AMF) ) 182a, 182b and so on. As shown in FIG. 1D, the gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

The CN 115 shown in Figure 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are described as being part of CN 115, it should be understood that any of these elements may be owned and/or operated by entities other than the CN operator.

The AMFs 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as control nodes. For example, AMFs 182a, 182b may be responsible for authenticating users of WTRUs 102a, 102b, 102c, supporting network slicing (eg, handling different PDU sessions with different needs), selecting specific SMFs 183a, 183b, managing registration areas, terminating NAS Communication and mobility management, etc. The AMFs 182a, 1823b may use network slicing to customize the CN support provided to the WTRUs 102a, 102b, 102c based on the type of service used by the WTRUs 102a, 102b, 102c. For example, different network slices can be created for different use cases, This use case is, for example, services that rely on Ultra Reliable Low Latency (URLLC) access, services that rely on Enhanced Massive Mobile Broadband (eMBB) access, and/or services for Machine Type Communication (MTC) access and many more. AMF 162 may provide for handover between RAN 113 and other RANs (not shown) using other radio technologies such as LTE, LTE-A, LTE-A Pro and/or non-3GPP access technologies such as WiFi control plane functionality.

The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via the N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via the N4 interface. The SMFs 183a, 183b can select and control the UPFs 184a, 184b and can configure traffic routing via the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. PDU conversation types can be IP-based, non-IP-based, and Ethernet-based, among others.

The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to a packet-switched network (eg, the Internet 110 ) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices, the UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions , handles user plane QoS, caches downlink packets, provides mobility anchors, and more.

CN 115 may facilitate communication with other networks. For example, CN 115 may include, or may communicate with, an IP gateway (eg, an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN 115 and PSTN 108 . In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, including other wired and/or wireless networks owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local data network (DN) 185a, 185b via an N3 interface interfacing with UPFs 184a, 184b and an N6 interface between UPFs 184a, 184b and DNs 185a, 185b and via UPFs 184a, 184b .

In view of the corresponding descriptions of FIGS. 1A-1D and 1A-1D, one or more or all of the functions described herein with respect to one or more of the following may be implemented by one or more simulation devices (not shown) to perform: WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185 a-b and/or any other device(s) described herein. These emulation devices may be one or more devices configured to emulate one or more or all of the functions herein. For example, these simulated devices may be used to test other devices, and/or simulate network and/or WTRU functionality.

A simulated device may be designed to perform one or more tests of other devices in a laboratory environment and/or an operator network environment. For example, the one or more emulated devices may perform one or more or all functions while being implemented and/or deployed in whole or in part as part of a wired and/or wireless communication network to test other functions within the communication network device. The one or more emulated devices may perform one or more or all of the functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device to perform testing, and/or may use over-the-air wireless communication to perform testing.

The one or more emulated devices may perform one or more functions, including all functions, while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the simulation device may be used in a test lab and/or test scenario of a wired and/or wireless communication network that is not deployed (eg, tested) to perform testing of one or more components. The one or more simulation devices may be test equipment set. The emulation device may transmit and/or receive data using direct RF coupling and/or wireless communication via RF circuitry (eg, the circuitry may include one or more antennas).

In a wireless system, such as the wireless system described herein in relation to Figures 1A through 1D, a central node (eg, a gNB) may serve a set of WTRUs, and a central node (eg, a gNB) may serve a set of WTRUs and transmit transport blocks (TBs) from the WTRUs to the central node. One or more occasions may be managed by the central node. For example, the gNB may schedule respective WTRU uplink (UL) transmissions by assigning separate time-frequency resources to each WTRU and granting each resource to one WTRU. This arrangement of UL transmissions is sometimes referred to as grant-based UL transmissions. Alternatively, the gNB may advertise the existence of one or more time-frequency resources and allow a group of WTRUs to use each resource, thus allowing access without a specific UL grant.

In some cases, the unlicensed frequency band may be used exclusively or partially in a wireless system where a base station (eg, a gNB) or WTRU needs to perform listen-before-and-transmit (LBT) before accessing an unlicensed wireless channel to ensure fair channel storage. Pick. Depending on the regulatory requirements for unauthorized access, LBT specifications can be different. In general, LBT procedures may include fixed and/or random duration intervals in which a wireless node (eg, a gNB or WTRU) listens to the medium, and if the detected energy level from the medium is above a threshold (specified by the regulator), The gNB or WTRU then refrains from transmitting any wireless signals; otherwise, the wireless node may transmit its desired signal after this duration (ie, the LBT procedure is complete). The LBT duration interval is the time spent detecting/sensing before a transmission, which means that a longer LBT duration interval means longer waiting time for transmission.

In general, NR technology can be applied to many use cases such as Ultra-Reliable Low-Latency Communications (URLLC), Large Machine Type Communications (mMTC or MMTC), or Enhanced Mobile Broadband (eMBB or EMBB) communications. MMTC enables low-cost, high-volume, battery-operated inter-device communication designed to support applications such as smart metering, logistics, and field and body sensors. URLLC can Enables ultra-reliable, very low-latency, and high-availability communications of devices and machines for applications such as vehicle communications, industrial control, factory automation, remote surgery, smart grids, and public safety applications. EMBB can address enhancements in various parameters such as data rate, latency, and mobile broadband access coverage. To meet the performance requirements of these use cases, NR can have specific parameters and capabilities.

NR may specify various parameter sets ranging from 15KHz to 240KHz subcarrier spacing. The base subcarrier spacing may be 15KHz and other parameter sets may have increased subcarrier spacing, which is the product of a power of 2 and the base subcarrier spacing, listed in Table 1 below.

個資源塊(由較高層參數CORESET-freq-dom給出)、以及在時域中的

個符號(由較高層參數CORESET-time-dur給出)。給到PDCCH的一些相關參數可以是：群組公共(GC)PDCCH，RRC配置的；公共PDCCH，針對所有WTRU的系統資訊及傳呼；剩餘系統資訊(RMSI)，由PBCH配置的；其他系統資訊(OSI)，由PBCH配置的。 The Physical Downlink Control Channel (PDCCH) in NR may include one or more Control Channel Elements (CCEs); up to 16 CCEs depending on the aggregation level. The control resource set (CORESET) can be included in the frequency domain

resource blocks (given by the higher layer parameter CORESET-freq-dom ), and in the time domain

symbols (given by the higher layer parameter CORESET-time-dur ). Some relevant parameters given to PDCCH may be: group common (GC) PDCCH, configured by RRC; common PDCCH, system information and paging for all WTRUs; residual system information (RMSI), configured by PBCH; other system information ( OSI), configured by PBCH.

The Physical Uplink Control Channel (PUCCH) in NR can support multiple formats, as shown in Table 2.

In the NR frame, the OFDM symbols in the slot can be classified as 'downlink' (denoted as 'D'), 'flexible' (denoted as 'X'), or 'uplink' (denoted as 'U') '). Table 3 shows this structure.

In some regulatory regimes, first listen and wait (LBT) procedures are mandatory for unauthorized channel use, and thus for protocols such as Authorized Assisted Access (LAA), Enhanced LAA (eLAA), and Further eLAA (feLAA) can be There are LBT categories. The LBT Category 4 (CAT 4) scheme employed in LAA/eLAA may be the preferred scheme for some use cases. The LBT CAT 4 procedure may begin when the eNB or gNB and in some cases the WTRU wants to transmit control or data in an unlicensed channel. The device may then perform an initial clear channel assessment (CCA), where the channel is checked to be free for a period of time (ie, the period of time is the sum of a fixed period of time and a pseudo-random duration). Channel availability is then determined by comparing the detected energy (ED) levels across the bandwidth of the unauthorized channel to the energy threshold determined by the regulator.

If the channel is determined to be free, the transmission can take place. If it is not idle, the device performs a slotted random backshift procedure in which random numbers can be selected from a specified interval called a contention window. The backshift countdown can be obtained and the channel is verified to be free, and a transmission can be initiated when the backshift counter becomes zero. After an eNB or gNB has gained access to a channel, it may be allowed to transmit for a duration called Channel Occupancy Time (COT) (but only for a limited duration called Maximum Channel Occupancy Time (MCOT). CAT 4 LBT procedures with random back-off and variable contention window size can achieve fair channel access and good coexistence with other radio access technologies (RATs) such as Wi-Fi and other LAA networks. The following are examples of LBT classes: class 1 no listening interval; class 2 fixed duration listening interval (eg 25 μs); class 3 random duration listening interval with fixed contention window; and class 4 with increased contention The window's random duration listening interval.

In class 3 LBT, the transmitter can extract the random number N within the contention window. The size of the contention window can be specified by the minimum and maximum values of N. The size of the contention window can be fixed. In LBT procedures, the nonce N can be used to determine the duration for which the channel is sensed to be idle before the transmitting entity transmits on the channel.

In Category 4 LBT, the transmitter can extract the random number N within the contention window. The size of the contention window can be specified by the minimum and maximum values of N. The transport entity may change the size of the contention window when extracting the nonce N. In LBT procedures, the nonce N can be used to determine the duration for which a channel is sensed to be idle before a transmitting entity transmits on the channel.

As described herein, a carrier bandwidth portion (BWP) may be a contiguous set of physical resource blocks selected from a contiguous subset of common resource blocks for a given parameter set on a given carrier.

A WTRU may be configured with up to four carrier BWPs in the downlink, where a single downlink carrier BWP is active at a given time. The WTRU may not be expected to receive PDSCH, PDCCH, CSI-RS or TRS outside the active BWP. A WTRU may be configured with up to four carrier BWPs in the uplink, where a single uplink carrier BWP is active at a given time. If the WTRU is configured with supplemental uplink, the WTRU may also be configured with up to four carrier BWPs in supplemental uplink, where a single supplemental uplink carrier BWP is active at a given time. The WTRU may not transmit PUSCH or PUCCH outside the active BWP,

For HARQ operation in NR, the 3-bit PDSCH to HARQ timing indicator field may indicate flexible HARQ feedback timing. There may be a one-to-one mapping between the corresponding feedback on PDSCH and PUCCH/UCI. The slot timing between PDSCH and PUCCH (referred to as K1) can be indicated in a 3-bit field in DCI, indexing the values of the eight RRC configurations. In DCI format 1-1, these eight values can be mapped to RRC-configured delay values (ie, the mapping is {000,...,111}->RRC-defined values). In DCI format 1-0, these eight values are mapped to the delay set {1,2,...,8}.

NR may support small processing delays, but no less than providing feedback in the same time slot (eg, for a Capability 1 WTRU). For example, for a subcarrier spacing of 30KHz, the L1 processing delay from the end of PDSCH to the beginning of PUCCH may be a minimum of 10 OFDM symbols. N1 may be the number of OFDM symbols from the end of PDSCH to the beginning of PUCCH. The frontload DMRS may only be 10 and 17 symbols for SCS=30kHz and 60kHz, and the frontload+additional DMRS may be 13 and 20 symbols for SCS=30kHz and 60kHz. N2 may be the number of OFDM symbols from the end of the PDCCH (ie, the UL grant) to the beginning of the PUSCH. Frequency-first RE-mapping (Freq.-first RE-mapping) can be 12 and 23 symbols for SCS=30 kHz and 60 kHz.

NR can support dynamic indication of PUCCH resources and time, and can use a single HARQ codebook to send HARQ feedback for multiple PDSCHs. In the case of dynamically scheduled transmission, the PUCCH resource and time may be indicated in the scheduled DCI. The association between PDSCH and PUCCH may be based on the PUCCH resource and time indicated in the scheduled DCI; the HARQ feedback for all PDSCHs for which the scheduled DCI indicates the same PUCCH resource and time may be reported together. The most recent PDSCH feedback that can be included may be limited by the processing time required by the WTRU to prepare the HARQ feedback.

NR may use semi-static or dynamic codebooks to aggregate feedback from multiple HARQ processes in one PUCCH.

For semi-static NR feedback aggregation, the ACK codebook size may be determined based on the cross-PDCCH monitoring opportunities and the maximum number of TBs of a cell in times that can be configured for ACKs on the same time slot. This mode is more robust to loss and erroneous DCI detection than dynamic mode, but The price is that more bits are needed for ACK feedback. For example, using 8 CBGs and 16 HARQ processes, 128 bits per cell are transmitted to a single HARQ feedback, even for a single TB.

For dynamic NR feedback aggregation, the set of HARQ processes may be dynamically determined for each HARQ process for which feedback should be reported. In general, the HARQ codebook size may be determined based on the content of multiple consecutively received DCIs, based on which the gNB efficiently communicates the codebook attributes to the WTRU. The Downlink Assignment Indicator (DAI, 2 bits) may indicate the number of HARQ processes that should be reported; DAI may make it robust to loss/error DCI. To index the HARQ codebook, the DCI of each scheduled assignment may contain DAI that counts all previous DL assignments including the current assignment, which may be included in the HARQ codebook. The DAI contained in the DCI of the most recent DL assignment may determine the HARQ codebook size. Even if the WTRU loses some DL assignments, it can still properly address the HARQ codebook, as long as the DAI does not wrap around. The DAI in the DL scheduled DCI is stepped down by 1 compared to the immediately preceding DL scheduled DCI; if the difference is greater than 1, it can indicate that the PDCCH has been lost.

There may be one or more HARQ procedures for unlicensed UL transmission in NR. Grant-free (GF) UL transmissions (also known as configuration grants) and associated HARQ procedures can have several types and properties in NR. Type I may only be configured via RRC, where the WTRU is configured to access GF resources. Type II may be with RRC configuration and DCI signaling, where the WTRU is configured to access GF resources, and access to GF resources is enabled, disabled, or restarted using DCI signaling. GF UL transmission can be configured to occur on a slot-based or mini-slot-based.

A property of the HARQ procedure may be acknowledgment, HARQ feedback and retransmission as follows: Grant-based TB retransmission after GF transmission failure; and, if the WTRU receives an implicit acknowledgment indication, up to K=8 times across consecutive GF resources Repeated license-free TB transfers with early termination.

The implicit HARQ attribute may be that there is no explicit HARQ-ACK feedback, and its use may be implicit in the NDI field in the DCI format that explicitly indicates the UL HARQ process ID. Additionally, the implicit HARQ attribute may be where the HARQ ID is from the selected resource; the HARQ process ID may be equal to floor(X/UL-TWG-periodicity) mod UL-TWG-numbHARQproc, where X=(SFN * SlotPerFrame * SymbolPerSlot+Slot_index_In_SF * SymbolPerSlot+Symbol_Index_In_Slot), and X is the symbol index where the repeating bundle starts. Furthermore, the implicit HARQ attribute may be the HARQ RV sequence, which is determined by the RRC configuration (including RV cycle and RV0 repetition).

HARQ can also be periodic, with multiple TX opportunities for repetition in each cycle. Additionally, HARQ TX opportunities can be tied to a certain RV order, eg, {0,2,3,1}, {0,3,0,3} and {0,0,0,0} may be supported. The repeated initial TX can start from RV0, but its timing can be flexible.

In an unlicensed NR (NR-U) environment, when an NR-U device attempts to access an unlicensed channel, it may contend with inter-RAT devices as well as intra-RAT devices for channel access. The type and density of inter-RAT devices may depend on the unlicensed channel and the RAT may be Wi-Fi, LTE LAA, Bluetooth, or the like. Intra-RAT devices may be other NR-U devices (eg, WTRUs or gNBs). For example, for an NR-U WTRU, the intra-RAT device may be other NR-U WTRUs connected to the same gNB, or it may be an NR-U gNB or WTRU that is not associated with the same gNB. In attempting to access unlicensed channels, the NR-U WTRU or gNB may need to compete fairly and coexist with inter-RAT and intra-RAT devices.

To ensure fair competition and coexistence, in some regulatory domains, it may be required (ie, mandated) that when a wireless node wants to access an unauthorized channel, the node needs to first perform a listen-before-to-bend (LBT) procedure for a period of time; and if If no energy above the threshold is detected, the wireless node can be allowed to allow transmission to the wireless channel for up to the maximum duration. Therefore, for NR-U nodes, a similar LBT procedure can be expected.

Figure 2 is an example transmission diagram where the WTRU fails to successfully complete the LBT. As described herein, for any transmission graph, time 201 may be indicated on the horizontal axis, with transmissions having multiple units of time (eg, time slots). A time slot may be marked in time relative to time slot n. In this example, at 210, the WTRU may receive DL for PDCCH in time slot n-2 and time slot n-1, which may indicate UL resources for PUCCH in time slot n+2. At 211, the WTRU may not be able to successfully complete the LBT for the scheduled PUCCH at slot n+2, and thus may need to limit transmission of the HARQ codebooks prepared for the TBs carried in slots n-2 and n-1. Then, the WTRU in this case may have to limit the transmission even if the transmission has timing dependencies that may affect the receiving entity. For example, if the WTRU is to transmit a PUCCH including a HARQ codebook and the LBT fails, the WTRU may have to limit transmission of the PUCCH. At 212, the NR gNB may assume that the relevant TB in the previous PDSCH (for which the WTRU has prepared a HARQ codebook for transmission) was not correctly received by the WTRU and the gNB may need to transmit on the next (eg, next time slot n- The TB is retransmitted in 2 and n-1).

Figure 2 illustrates that in some cases, the NR-U gNB may not receive the HARQ codebook due to the WTRU failing to complete the LBT process for the scheduled PUCCH resources. One way to address this problem may be to allow multiple occasions for PUCCH transmission (eg advertised in DCI).

Figure 3 is an example transmission diagram where a WTRU may have more than one occasion for PUCCH. Time 301 is indicated on the horizontal axis, with multiple time units (eg time slots). Time slots are marked in time relative to time slot n. In this example, at 310, the WTRU may receive the DL of the PDCCH (ie, in time slot n-2 and time slot n-1), which may indicate PUCCH in time slot n+2 and time slot n+4. At 311, the WTRU may attempt to transmit in the first indicated opportunity of slot n+2, but The LBT fails and therefore must wait until the next opportunity (ie, slot n+4). At 313, the WTRU tries again and successfully completes the LBT in slot n+4 and transmits on the PUCCH.

In general, multiple resource opportunities can be scheduled on multiple time slots that are spread out in time, or can be on the same or two consecutive time slots but each at a different 20MHz BWP (ie, each at a different 20MHz The multiple resource opportunities can be scheduled within the unauthorized channel). Therefore, the PDSCH to HARQ timing indicator field, which is a scalar in NR, can carry multiple values. If the LBT is successful, the WTRU may select the first time slot, otherwise proceed to the next time slot, and so on. In the example of Figure 3, the WTRU failed to successfully complete LBT for the first scheduled PUCCH at slot n+2, and waited for the second scheduled PUCCH at slot n+4, at slot n+4 , the WTRU successfully completes the LBT and transmits the HARQ codebook prepared for the TB (ie PDSCH) carried in time slots n-2 and n-1. The scheduled set of PUCCHs may be indicated in the set of PDSCH to HARQ timing indicators.

However, the multiple timing approach has disadvantages. When the LBT has failed in the first opportunity (eg, slot n+2 in Figure 3), the chance that the LBT succeeds at the next opportunity (eg, slot n+4 in Figure 3) can be referred to as the channel occupancy coherence time (COCT) and may depend on how many inter-RAT and intra-RAT devices operate in unauthorized channels and what type of traffic each device participates in. For example, if the majority of the traffic of unlicensed devices active in the band is video traffic, the COCT may be large, and the chance of a successful LBT following a failed LBT may be high, as long as the first LBT observation Two LBT observations are long enough. If the COCT is large, scheduling multiple PUCCH resources within the same COT may have no effect, which may have a duration of less than 5ms or 10ms depending on the class for which the COT is established. Assigning multiple PUCCH opportunities per WTRU may be wasteful because the gNB must assign multiple PUCCH resources (ie, it may double or triple the number of resources for PUCCH).

Furthermore, if the WTRU fails to transmit PUCCH within the opportunity window and LBT has failed on some PUCCH resources, the gNB may still not have the flexibility to request feedback at a later time. In HARQ in NR-U it is possible to first stay in the NR procedure where only one slot for PUCCH transmission is indicated in each PDCCH. However, if the gNB does not receive the expected PUCCH, the gNB may provide one or more supplementary transmission opportunities for the PUCCH, giving the WTRU another opportunity to transmit the HARQ feedback that was not previously sent and possibly other HARQ feedback (ie, may indicate more than one time slot for PUCCH transmission). Furthermore, even if the WTRU completes the LBT and sends the HARQ feedback, the gNB may not correctly detect the HARQ feedback due to interference or collisions, which can lead to misalignment between the gNB and the WTRU.

Efficient resource scheduling for PUCCH transmission in the NR-U scenario can address these issues. To reduce overhead, a WTRU may be assigned exclusive resources (which are assigned to each WTRU) and inclusive resources (which are shared among multiple WTRUs). Inclusive resources may be assigned in a manner that reduces the probability of collisions between WTRUs. To implement the above, each WTRU may be assigned some exclusive PDSCH to HARQ timing indicators, and one or more non-exclusive PDSCH to HARQ timing indicators (which may be shared among multiple WTRUs). The gNB may prioritize WTRUs using the Inclusive PDSCH to HARQ timing indicator.

To implement prioritization of some WTRUs to manage inclusive resources, the PDSCH to HARQ timing indicator may include a prioritization parameter (eg, a channel access priority level that determines the priority that the WTRU uses to access the medium to transmit its HARQ feedback) . The gNB may explicitly assign the WTRU a prioritization parameter for a particular inclusive resource. This can be assigned statically (ie by RRC configuration), semi-statically (ie by a combination of RRC configuration and DCI) or dynamically (ie by DCI).

In another approach, the WTRU may automatically select its access priority level for a particular inclusive resource. For example, the WTRU may select the priority parameter based on the number of inclusive resource failures it has experienced. Alternatively, the WTRU may select the priority parameter based on the number of exclusive and inclusive resources it is assigned to. To this end, it may be assumed that the WTRU has N=N1+N2 HARQ resources, where N1 represents exclusive resources and N2 represents non-exclusive resources. In one example, the access priority level for N2 may be fixed and depend on the WTRU or traffic type. In another example, the access priority level may change as N2 increases (eg, N2,1>=N2,1>=N2,3, where N2,x is the xth N2 resource). In another example, the access priority level may depend on the values of N1 and N2, eg, a WTRU with N1=3 and N2=1 may have lower priority than a WTRU with N1=1 and N3=3 .

Figure 4 is an exemplary transmission diagram that a WTRU may have prioritization for non-exclusive PUCCH. Time 401 is displayed on the horizontal axis and can be divided into time increments (eg time slots) relative to some n increments. In any of the figures described herein, "space" may refer to a break in the figure, for example purposes only, and is not intended to indicate missing or non-sequential time increments, but only for the purpose of illustrating Save space in the example. Additionally, a space may be the same as or similar to a slot preceding or following a space, unless otherwise specified.

In the example of FIG. 4, at 410, WTRU 1 may receive a PDCCH in slot n-2 with an indication of exclusive PUCCH resources in slot n+2 and priority in slot n+4 Indication of the non-exclusive PUCCH slot with sequence parameter 1. WTRU 1 may receive and decode the PDSCH in slot n-2, and for PDSCH, WTRU 1 may need to send HARQ feedback. At 411, WTRU 2 may receive a PDCCH in slot n-1 with an indication of exclusive PUCCH resources in slot n+3 and an inclusive PUCCH with a priority parameter of 2 in slot n+4 Time slot indication. In this example, WTRU 2 may have a lower priority. WTRU 2 may receive and decode the PDSCH in slot n-1 for which WTRU 2 may need to send HARQ feedback.

For the purposes of this example, it may be assumed that the gNB did not receive a transmission from WTRU 1 or WTRU 2 in the PUCCH to which WTRU 1 or WTRU 2 was assigned (ie, slot n+2 or n+3, respectively). For example, at slot n+2, WTRU 1 may have performed LBT to transmit in the PUCCH where the LBT failed, and thus WTRU 1 may have been unable to send the transmission in that PUCCH and must wait until slot n+4. Similarly, at slot n+3, WTRU 2 may have performed the failed LBT, and the WTRU must wait until slot n+4.

Due to the failed first PUCCH attempts for these two WTRUs, at 412 WTRU 1 and WTRU 2 may compete for PUCCH resources in slot n+4, WTRU 2's LBT duration is set to be statistically longer than WTRU 1's LBT The value of time is a longer value, thus increasing the probability that WTRU 1 acquires resources for transmission (ie, WTRU 1 has higher priority) because WTRU 1 has less latency before it transmits according to the LBT procedure. Since WTRU 1 has priority, it can successfully transmit its HARQ feedback.

In some cases, the gNB may not be able to detect the HARQ feedback sent by the WTRU due to collision/interference at the gNB side. The reason why the gNB is not able to receive the transmission (eg failed LBT or lost UCI transmission) is not discerned on the gNB side. Due to the temporal association between the PDSCH and the corresponding feedback, if the gNB fails to detect the feedback at a predefined time position, the gNB can then retransmit all corresponding PDSCHs. While this can happen in NR operation in a licensed channel, in NR-U it happens more frequently on the gNB side due to highly fluctuating interference and possible collisions on the gNB side due to hidden nodes etc. (eg undetectable on the WTRU side) . This can cause misalignment between the gNB and the WTRU (which With regard to which HARQ codebook of the previous PDSCH has been successfully received by the gNB), this may pose a risk for the WTRU to refresh the HARQ codebook prematurely.

Figure 5 is an example transmission diagram where the WTRU successfully completes the LBT but the gNB fails to detect the PUCCH. Time may be displayed on the horizontal axis 501 as time slot increments. At 510, the WTRU may receive indications for PUCCH at slot n+2 in slots n-2 and n-1, and may also receive and decode PDSCH in each slot. At 511, the WTRU may successfully complete the LBT and transmit the HARQ feedback for the scheduled PUCCH at slot n+2, but the gNB fails to detect the transmission due to interference or errors at the receiver. At 512, the gNB may send the next PDCCH to the WTRU in slot n+4 indicating that the PUCCH scheduled at slot n+6 is a supplemental PUCCH. The supplemental PUCCH may include a HARQ codebook for the WTRU to transmit in the PUCCH in time slot n+6 for the previously scheduled PUCCH that should have been received in time slot n+2, and a HARQ codebook for time slot n +4 for any codebook associated with the PDSCH. At 513, the WTRU may successfully complete the LBT and transmit the PUCCH with all HARQ codebooks in the supplemental assigned resources in slot n+6.

Unlike the example of Figure 5, the problem of the gNB not receiving the expected PUCCH may occur in consecutive attempts, eg spanning a single Channel Occupancy Time (COT) or spanning two COTs, etc. For example, the gNB may not receive the expected PUCCH carrying the HARQ codebook for the first PDSCH resource set, and the gNB may transmit the given first supplemental PUCCH resource for the HARQ codebook, but until the time of the supplementary resource , the gNB may keep scheduling more PDSCHs (ie, a second PDSCH resource set) for the WTRU; thus, there may be other HARQ feedback or other HARQ codebooks on top of the previous one or more HARQ codebooks. The WTRU and the gNB may need to have the same understanding of how much and what HARQ codebook the WTRU needs to transmit, and this common understanding may need to be achieved by keeping at least the amount of control information short for DCI. Even during the first supplemental PUCCH resource, The WTRU may not be able to send the aggregated HARQ feedback (eg, due to LBT failure) or the gNB may not successfully detect the codebook, then the gNB may give the WTRU another chance by assigning a second supplemental PUCCH resource, but until the supplementary resource , the gNB may schedule another PDSCH resource set (ie, a third PDSCH resource set) for the WTRU. It may now be desirable for the WTRU to aggregate the HARQ feedback for all three PDSCH resource sets and transmit them during the second supplemental PUCCH resource. This situation continues until some point during the same COT where there are no scheduled occasions for aggregated HARQ codebooks, which means that these codebooks are postponed to the next COT. Furthermore, in the case where the gNB sends a supplemental transmission opportunity, a misalignment between the codebook size expected by the gNB and the actual codebook size sent by the WTRU may result.

To address this, additional fields in the DCI may indicate to the WTRU that the upcoming PUCCH is a "supplemental transmission" and allow the WTRU to calculate the codebook size as it did in previous PUCCH transmissions. The Extended Downlink Assignment Indicator (EDAI) may be an additional field for the NR-U scenario described herein. This field in the DCI can carry the attributes of the scheduled PUCCH. This field can take into account PDSCH resource sets or groups with consecutive Downlink Assignment Indicators (DAIs) and mark them as groups. The EDAI field may have a value of 0 if the WTRU is expected to form a HARQ codebook for TBs within the current PDSCH resource set or group. The EDAI field may have a value of 1 if the WTRU is expected to form HARQ codebooks for TBs within the current PDSCH resource set or group and for TBs within the immediately preceding PDSCH resource set or group. The EDAI field may have a value of 2 if the WTRU is expected to form a HARQ codebook for the TB within the current PDSCH resource set or group and the two immediately preceding TBs within the PDSCH resource set or group. The EDAI field may have a value of 3 if the WTRU wishes to form a HARQ codebook for the TB within the current PDSCH resource set or group and the TBs within the immediately preceding three PDSCH resource sets or groups. Then, if the WTRU is expected The EDAI field may have a value of Y to form a HARQ codebook for the TBs within the current PDSCH resource set or group and the TBs within the immediately previous Y PDSCH resource sets or groups. As described herein, this general rule can be applied to other situations where a TB is replaced with some other time or group unit, so that the value of the EDAI field can be relative to the current time/group set as well as any previous time/group set (eg transmission, COT, etc.). Using this mechanism, a single DCI may request HARQ ACK feedback in the same PUCCH for all PDSCHs that may be transmitted in one or more PDSCH groups.

When EDAI is non-zero and the WTRU attempts to aggregate two or more previously prepared HARQ codebooks with the current codebook, the WTRU may insert fields between the bitstreams of one codebook and the next codebook to enable the gNB to distinguish and parses the codebook; this field can be represented as a HARQ codebook delimiter with a specified bit width (eg, 2 or 4). When aggregating multiple HARQ codebooks, the WTRU may insert a HARQ codebook delimiter after each HARQ codebook. In one example, if the WTRU has received consecutive PDCCHs with EDAI attributes that do not have consecutive values, the WTRU may presume that one or more sets of PDCCHs that result in discontinuous EDAI values have not been detected. In this case, the WTRU may insert one HARQ codebook delimiter for each missing EDAI value. For example, consider that the WTRU receives a PDCCH set with a value of EDAI=0, and then in the next set of slots or even the next one or more COTs, the WTRU receives a PDCCH set with a value of EDAI=2. This may indicate that the WTRU has lost one or more PDCCHs with EDAI=1, so the WTRU may not know how many TBs were transmitted during the one or more PDCCHs with EDAI=1. Thus, when the WTRU aggregates the codebooks for the first received set of PDCCH(s) with EDAI=0 and the second received set of PDCCH(s) with EDAI=2, the WTRU may The set of missing PDCCH(s) with EDAI=1 inserts other HARQ codebook delimiters. To further illustrate this, the WTRU may aggregate the following HARQ codebooks: HARQ codebook EDAI0, HARQ codebook Delimiter, HARQ codebook delimiter, HARQ codebook EDAI2. In this example, PDSCH groups (eg PDSCH in COT) are dynamically marked with each EDAI index. In this example, a HARQ codebook for each group indexed by the EDAI associated with the group may be accumulated within each PDSCH group. Alternatively, the HARQ codebook for each PDSCH group indexed by the EDAI associated with the group may be accumulated across all groups.

Figure 6 is the WTRU preparing HARQ according to DAI (ie, to calculate the codebook for the desired PDSCH set as expected by the gNB) and according to EDAI (ie, to decide how many immediately preceding HARQ codebook sets should also be included) Example transfer diagram for the codebook. At 610, the WTRU may receive an indication for the PUCCH in slot n+2 in slot n-2, where DAI=1 and EDAI=0. At 611, the WTRU may receive an indication for the PUCCH in slot n+2 in slot n-1, where DAI=2, since the codebook will be based on the set of two PDSCHs received so far, and EDAI=0. At 612, the WTRU will perform its scheduled LBT at slot n+2 and the gNB will not receive the PUCCH in this example because the LBT failed or the LBT was successful but there is interference at the receiver. At 613, the WTRU will receive the normal resource assignment (eg, PUCCH in n+6 with DAI=3 since this is the third PDSCH) but indicate EDAI=1 since the gNB did not receive it in slot n+2 PUCCH, thus indicating that the immediately preceding HARQ codebook set should also be included. At 614, the gNB will not receive the PUCCH, similar to the situation at 612 for illustration. Therefore, at the next resource assignment at 615, the WTRU may receive an indication of PUCCH for slot n+9, with DAI=3 and EDAI=2, since these two closest codebook sets should now be included. At 616, the gNB may finally receive the PUCCH after a successful LBT in the indicated slot n+9 by the WTRU.

Figure 7 is the WTRU according to the DAI (ie to calculate the codebook for the desired PDSCH set) and according to the last value of the EDAI (ie to decide how many immediately preceding HARQs should also be included) Codebook Set) to prepare an exemplary transmission diagram of the HARQ codebook. The value of EDAI may be different during the PDCCH resource set. For example, considering two consecutive PDCCH resources with consecutive DAI values at 712 and 714 (eg, in slots n+2 and n+4) indicates that the WTRU is expected to report an upcoming HARQ codebook for the associated PDSCH resource. PUCCH (eg in slot n+6). Furthermore, the PUCCH for the previous set of PDSCH resources at 710 and 711 (eg, in slots n-2 and n-1) may be queued between these two PDCCH resources (eg, in slot n+3) Procedure. At 712, (eg in the PDCCH in slot n+2) the value of EDAI may be 0, but when the gNB has not received the expected codebook for the previous PDSCH set at 713, then at the next PDCCH (eg, at slot n+2) n+4), the gNB may change the EDAI to 1 (at 714) and may also increase the size of the PUCCH (ie, it may even relocate the PUCCH resources to later slots to accommodate larger PUCCHs). At 715, the WTRU may then prepare an aggregated codebook that includes older HARQ codebooks (eg, codebooks that have not been received by the gNB for time slots n-2 and n-1) and new HARQ codebooks (eg, for time slots two PDSCH resources in n+2 and n+4).

The WTRU may calculate the dynamic codebook size with reference to the DAI value. Due to the 2-bit size of DAI, this field can wrap around after four PDCCH/PDSCH transmissions, all of which refer to the upcoming PUCCH. For example, if five consecutive PDCCH/PDSCH transmissions all refer to the upcoming PUCCH, the DAI values in the PDCCH may be "mod(dai,4), mod(dai+1,4), mod(dai+2,4 respectively) ),mod(dai+3,4),mod(dai,4),mod(dai+1,4)", which indicates the wraparound effect. However, if less than four consecutive PDCCHs are lost, the wraparound will not generate any errors (ie, the WTRU will simply report a NACK for the lost PDCCH resources since both the PDCCH and PDSCH are lost). Additionally, if the WTRU loses four or more consecutive PDCCH transmissions, the WTRU may not be able to calculate the actual number of lost PDCCH resources, which would result in Misalignment because there is no way to correctly calculate the size of the codebook. Losing 4 or more consecutive PDSCHs on the licensed carrier is unlikely, but more likely in NR-U due to collision/interference on the WTRU side. This problem can be solved by increasing the DAI size to more than 2 bits (e.g. 3 or 4 bits), making it less likely that 8 or 16 consecutive PDCCHs will be lost in cases where DAI is accumulated independently within each group ( That is, to accommodate the possibility of missing more than 4 PDCCHs). In the case of accumulating DAI across multiple PDSCH groups indexed by EDAI, the dynamic codebook size may be a multiple of the number (N) of PDCCH/PDSCH transmissions per group (ie, N x (3 or 4 bits) )).

Figure 8 is an exemplary transmission diagram for a WTRU to aggregate HARQ codebooks based on EDAI for one or more COTs. Here, the WTRU may aggregate the HARQ codebook from the earlier COT (ie, the immediately preceding COT in this example) (if the EDAI field indicates to do so (ie, EDAI=TBD1)). As shown, there may be two COTs 810 and 820. COT 810 may be a slot increment relative to n, and COT 820 may be a slot increment relative to j (eg, n=j). In general, there may be more than two COTs, but as shown, the COT 820 follows the COT 820. At 811 (ie slot n-2), the WTRU receives an indication of the PUCCH for slot n+2, where DAI= 1 and EDAI=0. At 812 (ie slot n-1), the PUCCH in slot n+2, where DAI=2 and EDAI=0, may be indicated to the WTRU.

At 813, the WTRU may be expected to transmit the HARQ ACK to the indicated PUCCH resource just at the end of the COT 810 (ie slot n+2), but the LBT may have been unsuccessful (eg, failed LBT or gNB failed to receive) and COT 810 ends without a WTRU transmission. The gNB as well as the WTRU may not know when the next opportunity for PUCCH transmission will be. To address this, at 821 (instant slot j), the gNB may send the PDCCH to the WTRU in the next COT 820 with an indication of EDAI=TBD1 (eg, in DCI or RRC). This indication indicates to the WTRU to send the PUCCH in slot j+k with the last PUCCH in the earlier COT 810 There is no aggregated HARQ codebook or HARQ codebook transmitted during the PUCCH occasion. The EDAI may indicate a specific PDSCH group or a specific COT, eg, a PDSCH group that cannot transmit PUCCH in the previous COT. At 822, the WTRU may successfully complete LBT for the PUCCH (eg, DCI-indicated or RRC-configured), and aggregate and send HARQ ACKs from previous and current COTs to the gNB. Although only two COTs are discussed in this example, the same technique can be used for one or more COTs.

In general, if the WTRU fails to complete the LBT and is restricted from transmitting PUCCH, the WTRU may keep the HARQ codebook until the next COT, and if the WTRU receives a PDCCH with EDAI=TBD1, the WTRU may do one of the following: 1) If DCI Indicates only the upcoming PUCCH, without any PDSCH, the WTRU may transmit the codebook in the indicated upcoming PUCCH resources; or, 2) If the DCI indicates the upcoming PUCCH and PDSCH resources, the WTRU may aggregate the earlier PUCCH resources The codebook and any new HARQ codebook and the aggregated codebook are transmitted in the indicated upcoming PUCCH resources. Even if the WTRU successfully completes the LBT procedure and transmits the PUCCH, the WTRU may keep the HARQ codebook until the next COT and/or until the WTRU receives a PDCCH with a value less than EDAI=TBD1 (eg, EDAI=0), after which the WTRU may discard the previous HARQ codebook.

If the EDAI has a bit width of 2, the TBD1 value may be, for example, 3, or if the EDAI has a bit width of 3, the TBD1 value may be 7. Or TBD1 may be 1, where the value in the first unicast PDCCH to the WTRU in the new COT has the same interpretation as described above. As described herein, the EDAI value shown and used with respect to the example of Figure 8 represents a value that is used to indicate to the WTRU that at a certain group/time (eg, TB, COT, etc.) to aggregate all pending until the next uplink opportunity , and the value can be one or more numbers, letters and/or symbols that can convey this meaning.

In one scenario, there may be two consecutive COTs where the gNB has sent a TB to the WTRU, and the WTRU fails to complete the LBT during the scheduled PUCCH occasion, or the gNB fails to detect the PUCCH correctly, which can result in a failure on the WTRU side The set of two pending HARQ codebooks. Additionally, if the field EDAI has a value of TBD2 within the received DCI, it may indicate that the WTRU should aggregate the current COT's HARQ codebook (if any) in the scheduled PUCCH resources indicated in the same DCI with EDAI=TBD2 words) and the pending HARQ codebook (eg, each prepared during the first two immediately preceding COTs). In other scenarios, any EDAI value of TBD#, # may represent a value associated with the number of COTs (eg, counting the current and/or any previous COTs to reach that value). The EDAI value of TBD# may indicate the value associated with a particular COT.

In some cases, when the WTRU sends a HARQ codebook in a scheduled PUCCH, the WTRU will not discard the HARQ codebook unless the attribute of the next scheduled PUCCH has EDAI=0. This helps the WTRU to ensure that the gNB has correctly decoded the previously sent PUCCH and may not need to retransmit the HARQ codebook again.

Figure 9 is an exemplary transmission diagram where the PUCCH resource assignment is outside the current COT and the PUCCH from the later COT is used. In this example, there can be two COTs 910 and 920. At 901, the gNB may schedule the PUCCH at theoretical time slot n+3, which may be outside the current COT 910. If the PDSCH to HARQ timing indicator field in the PDCCH indicates a timing instance outside the determined current COT end time, the WTRU may infer that the scheduled PUCCH is outside the current COT 910 . At 902, if the WTRU determines that the scheduled PUCCH falls after the end of the current COT, the WTRU may not perform PUCCH transmissions and may maintain a pending HARQ codebook for upcoming transmissions. In the subsequent COT 920 established by the gNB, when the WTRU receives a new PDCCH with EDAI (eg, indicated in DCI or RRC), the PDCCH has Attributes of the scheduled PUCCH for time slot j+2. At 904, the WTRU may send the pending HARQ codebooks and any new codebooks (ie, aggregated HARQ ACKs) in the newly scheduled PUCCH. In the first PDCCH/DCI in the new COT, the gNB may set EDAI=TBD1, similar to the example in Figure 8, to indicate to the WTRU that it wishes to transmit pending HARQ codebooks with any newly formed HARQ codebooks . Note that the arrows show that the HARQ ACK for each of the PDSCHs is sent in slot j+2. Not shown in the figure, if the WTRU does not receive a new PDCCH received for the corresponding PDSCH in the current COT in the subsequent COT, the WTRU may transmit the associated HARQ codebook in the PUCCH resource provided by the higher layer.

In some examples, if the WTRU detects a PDCCH in the current COT, but the DCI does not include the PDSCH to HARQ timing indicator field, the WTRU may consider that the gNB has not allocated PUCCH resources to the WTRU for the corresponding PDSCH reception in the current COT. Therefore, the WTRU may transmit pending HARQ codebooks on PUCCH resources in subsequent COTs, similar to the examples of Figures 8 and 9. In this case, assuming that the WTRU receives the PDSCH in slot n in the current COT, the WTRU may determine the PUCCH resource in slot n+k in the subsequent COT, where k is the higher layer, or DCI received in the subsequent COT The number of slots provided by the PDSCH to HARQ Timing Indicator field in .

In some cases, if the WTRU finds that the scheduled PUCCH falls after the end of the current COT, the WTRU may transmit the PUCCH after performing an appropriate LBT procedure and after the COT has ended. Even if the COT duration has expired, the WTRU may still transmit its PUCCH as any device in the unlicensed channel (eg, but not subject to the COT), however, the WTRU may have to perform an LBT procedure, the type of which depends on the scheduled How long the process's PUCCH is after the end of the COT. If the scheduled PUCCH is within 16 μs of the end of the COT, the WTRU PUCCH with Cat-1 LBT (which can be considered similar to no LBT) may be transmitted. If the scheduled PUCCH is within 25 μs of the end of the COT, the WTRU may transmit the PUCCH with a Cat-2 LBT (which may be referred to as a one-shot LBT). If the scheduled PUCCH is 25 μs after the end of the COT, the WTRU may transmit the PUCCH with Cat-3 LBT, and the WTRU may use the highest priority level to calculate the listening interval. If the scheduled PUCCH is 25 μs after the end of the COT and the WTRU is to transmit the TB within the configured grant resources after the PUCCH transmission, the WTRU may transmit the PUCCH with Cat-4 LBT. In the above case, since the gNB may require the WTRU to retransmit the HARQ codebook (ie, by setting EDAI=TBD1), the WTRU may keep the HARQ codebook until the next COT established by the gNB.

As described herein, for successful operation in the NR-U LBT procedure, LBT can be an efficient way for inter-RAT as well as intra-RAT coexistence. However, the listening interval in LBT is a waste of bandwidth resources, and the more frequently the LBT procedure is called, the lower the efficiency of channel access. Therefore, it is beneficial to have one handover from DL to UL in the COT so that the LBT procedure can be invoked once. The gNB may be able to use a single switch point to schedule DL/UL for the WTRU in the COT with no or very small gaps. If there are LBT rules for gaps smaller than 16 [mu]s (which can be obtained in LBT category-1), the provisions help with this, and if the gap is smaller than 16 [mu]s, the echoing device (eg, WTRU) does not have to perform any listening interval. For example, some 802.11 technologies can take advantage of this and a replying station can send an acknowledgment reply in a frame of just 16 [mu]s duration. Therefore, the NR-U frame structure can be modified for these efficient coexistence scenarios without LBT in the COT, where the gNB can address multiple WTRUs within the COT.

For reference, handover gaps (from DL to UL) may be indicated and scheduled within the SFI as follows "DL(WTRU1), DL(WTRU2), LBT, UL(WTRU1), DL(WTRU3), LBT, UL(WTRU2), DL(WTRU1),..." where, depending on the parameter set, the switching gap may be a OFDM symbols, and the duration of the gap can be greater than 16 μs. In such a case, the WTRU may need to perform operations other than Cat-1 LBT (eg, if the duration is less than 25 μs, the WTRU may perform Cat-2 LBT). However, performing LBT may mean that the WTRU must be in receive mode despite using a limited portion of its baseband unit, and means that by the time the WTRU successfully completes the LBT, the WTRU may require some switching time to switch to transmit mode.

In one scenario, the gNB may schedule multiple WTRUs in a manner that does not require DL/UL switching gaps. This may be a scheduling issue for the gNB, so the DL symbols are addressed to the first WTRU and the following UL symbols are for the second WTRU. For example, the schedule may be DL(WTRU1), DL(WTRU2), UL(WTRU1), DL(WTRU3), UL(WTRU2), DL(WTRU1), . . . In this example, WTRUl may be notified of its upcoming UL transmission and also be notified to prepare for UL transmissions without gaps.

In general, for these examples on switching UL/DL, slot boundaries can be deliberately ignored, however it is understood that UL symbols can be located in the last symbols of a slot. Furthermore, the DL and UL parts may have different sizes. Furthermore, the label DL (WTRU1) may represent, for example, one or more DL symbols at the beginning of the slot for the first WTRU (ie, WTRU1), which may carry PDCCH and/or PDSCH resources.

Figure 10 is an example transmission diagram where the WTRU checks the properties of the scheduled PUCCH resources and if no LBT-PUCCH has a true value, the WTRU does not perform any listening interval (ie, no gaps) just before the PUCCH. At 1011, the WTRU may use the matching RNTI to check the properties of the scheduled PUCCH resources in the DCI in the PDCCH; here the gNB may indicate to the WTRU that PUCCH in slot n+3, DAI=0, and no LBT-PUCCH= real. At 1012, the gNB may indicate to the WTRU that PUCCH in slot n+3, DAI=1, and no LBT-PUCCH=true. if No LBT-PUCCH has a true value, then the WTRU may infer that for the upcoming PUCCH (ie, slot n+3) (with associated time and frequency attributes), there is no gap just before the PUCCH UL transmission, so the WTRU may just No listening interval needs to be performed before the PUCCH, as shown at 1013. The gNB may schedule DL symbols preceding the PUCCH resource, so no DL channel is addressed to the WTRU.

Also at 1013, if the WTRU uses a matching RNTI to find the scheduled PUCCH resource in the DCI in the PDCCH, where no LBT-PUCCH subfield has a true value, the WTRU may temporarily overwrite the value of the most recent SFI (eg, only For the slot in which the PUCCH is located) and select one or more OFDM symbols preceding the scheduled PUCCH as the 'X' symbol during which the WTRU transitions from downlink reception to UL transmission. The WTRU may overwrite the most recent SFI value when determining the 'X' symbol, so that the gNB can take dynamic action to schedule PUCCH resources for the WTRU, which takes advantage of Cat-1 LBT (eg, or no LBT during the 16 μs period).

In another scenario, the gNB may provide a gap interval that is sufficient for the WTRU to perform a 25 μs LBT procedure (eg, one LBT) and switch from DL to UL symbols. The schedule may be "DL(WTRU1), DL(WTRU1), DL(WTRU1), DL(WTRU1), LBT, UL(WTRU1), ...", where the LBT duration exceeds one or two OFDM symbols (depending on in the parameter set). The WTRU may use the matching RNTI to check the PDCCH for the scheduled PUCCH resources in the DCI. If an LBT PUCCH has a value of TBD3, the WTRU may infer that for the upcoming PUCCH (ie, with associated time and frequency attributes), there is a gap of one or more symbols just before the PUCCH UL transmission, such that the WTRU is just before the PUCCH and A listening interval of 25 μs is performed just after the handover can be prepared in case the LBT is successful. If the WTRU uses a matching RNTI to find the scheduled PUCCH resource in the DCI in the PDCCH, where the No LBT-PUCCH subfield has a value of TBD3, The WTRU may then temporarily overwrite the value of the most recent SFI (eg only for the slot in which the PUCCH is located) and select one or more OFDM symbols preceding the scheduled PUCCH as the 'X' symbol (see Table 3, eg D/X /U symbol) during which the WTRU may transition from downlink reception to UL transmission. However, the transition may be conditional on a successful LBT during the 25 μs interval just before the transition.

In grant (GC) or grant-free transmissions configured in NR, the WTRU may be configured to repeat up to K=(1,2,4,8) times in a sequence of (ie, RRC-configured) grant-free resources Transfer TB. There are similar or identical grant-free procedures in NR-U, where some WTRU behavior with respect to channel access and related LBT procedures needs to be modified. When the gNB has established a COT with some license-free resources, the WTRU may start a license-free transmission within the COT established by the gNB. For unlicensed resources within the COT, the WTRU may perform LBT procedures to access the resources.

In an example, the WTRU may perform an LBT procedure (eg, LBT Cat-2, 3, or 4) once, eg, just before the first unlicensed resource that the WTRU attempts to access, and then if the LBT procedure is successful, the WTRU may LBT (ie LBT Cat-1) or one LBT (LBT Cat-2) or LBT Cat-3 within the COT to access the rest of the license-free resources. Depending on the value of K, the WTRU may reach the end of the COT without completing K repetitions of the TB (ie, as specified in the K repetition grant-exempt UL transmission).

In one example, the WTRU may perform the more robust LBT Cat-4 prior to accessing the first unlicensed resource outside the COT, and for accessing subsequent unlicensed resources outside the COT, the WTRU may perform no LBT or Cat-1 .

In one example, the WTRU may perform LBT Cat-3 prior to accessing the first unlicensed resource outside the COT, and for accessing subsequent unlicensed resources outside the COT, the WTRU may perform no LBT or one LBT.

In one example, the gNB may configure or may instruct the WTRU to perform an LBT procedure (Cat-1) once before the WTRU accesses the first and each subsequent license-free resource outside the COT.

In an example, the WTRU may restrict transmissions on resources other than COT.

As described herein, there may be situations in NR-U transmissions where the WTRU needs to transmit beyond the original COT and requires more than one COT. If there is more than one COT, the WTRU may need to send an acknowledgement in another COT and adjust the contention window.

For example, because the data transmission is in COT1 and the reply transmission can be in COT2, the transmission of the reply can be delayed to a separate COT. In this case, the acknowledgment transmission may follow a successful LBT. In one example, receipt of the HARQ codebook may also require an acknowledgement, eg, the WTRU performs LBT and transmits the UL acknowledgement in the UL slot. The gNB needs to acknowledge receipt of the acknowledgment in the subsequent DL slot. In this way, the WTRU can know if the transmission was successful and therefore the WTRU can adjust its contention window accordingly for the next LBT.

In the example where the ACK is in a separate COT, the UL acknowledgement transmission from the WTRU may be poll based. To improve efficiency, a group polling mechanism can be used.

In the example where the ACK is in a separate COT, the gNB may perform LBT to acquire the channel, and then the gNB may transmit the group common DCI to one or more WTRUs to acknowledge the poll. A set of frequency/time resources may be allocated for acknowledgement transmissions from multiple WTRUs. The WTRU may receive the group common DCI and have one or more UL acknowledgements to transmit and may transmit the acknowledgements using the allocated frequency/time resources. The WTRU may perform a fixed duration LBT prior to its UL transmission, or the WTRU may not need to perform LBT and just transmit in the allocated resources. In one example, the WTRU may randomly select one or more resources for transmission.

In the paradigm where the ACK is in a separate COT, the gNB may perform LBT to acquire the channel, and then the gNB may transmit a set of DCIs to a set of WTRUs to acknowledge the poll. A set of frequency/time resources may be allocated for acknowledgement transmissions from multiple WTRUs. The WTRU may receive the group common DCI with one or more UL acknowledgements to transmit, and may transmit the acknowledgements using the allocated frequency/time resources. In one example, the WTRU may randomly select one or more resources for transmission.

FIG. 11 is an exemplary procedure for contention window adjustment due to the cumulative number of acknowledgments to transmit.

In general, acknowledgment transmissions in NR-U may require LBT to be performed. The device may be unable to transmit due to LBT failure, or the device may transmit an acknowledgement but the transmission may fail due to a collision. In this case, the device can wait for the media/channel to become available again and perform LBT. If the transmission fails, the device may need to increase the contention window size so a larger random back-off value may be extracted. However, delayed acknowledgment transmission may result in delayed data transmission and congested channels. To address this, the device may reduce the contention window size or reduce the remaining backoff duration if there are accumulated replies. In this case, the device may have a separate random backoff procedure for acknowledgment transmissions.

CW _p

CW _max ，以及CW _min 以及CW _max 可以是被預定義/預定或傳訊的。在1104，WTRU可以提取用於應答傳輸的隨機後移數，R

[0,CW _p ]。在1106，WTEU可以偵測到信號能量等級在固定持續時間內低於預定義臨界值，以及WTRU可以具有未決的ACK/NACK。在1108，WTRU可以檢查是否R>0。 As shown in FIG. 11, at 1102, the WTRU may determine the contention window size CWp, where CW _min

CW _p

CW _max , as well as CW _min and CW _max may be predefined/predetermined or signaled. At 1104, the WTRU may extract a random backshift number for the acknowledgement transmission, R

[0, CW _p ]. At 1106, the WTEU may detect that the signal energy level is below a predefined threshold for a fixed duration, and the WTRU may have ACK/NACK pending. At 1108, the WTRU may check if R>0.

。WTRU可以保持更新的R值並繼續監視通道。 If R is greater than 0, then at 1110, the WTRU may continue to monitor the channel/media for the T time slot. If the channel is free during the time slot, then at 1114, the WTRU may set R=R-1. If not, then at 1112, the WTRU may check the number of accumulated acknowledgments, _Nack , to be transmitted, and the WTRU may set R = f ( R, _Nack ). The function f can be predefined or predetermined. In one example,

. The WTRU may maintain the updated R value and continue to monitor the channel.

If R is not greater than 0 (ie, R reaches 0), then at 1116, the WTRU may transmit an ACK/NACK to the gNB. At 1118, the WTRU may know/determine whether the transmitted ACK/NACK was successful. If successful, at 1020, the WTRU may set CW _p = CW _min and extract a new random backshift number for the next ACK/NACK transmission (at 1104). If the transmission of the ACK/NACK was unsuccessful, then at 1112, the WTRU may adjust the remaining random backshift value R. The WTRU may set R= f ( R, _Nack ).

，其中

可以是之前成功傳輸的應答的數量。 In the exemplary process of FIG. 11, the WTRU may have _Nack stored for the Acknowledgement Accumulation. The manner in which the N _ack is maintained on the WTRU side may be implementation dependent. For example, once the WTRU receives a valid DCI corresponding to a PDSCH transmission to the WTRU, the WTRU may increase the number of N _acks by one. The WTRU may reset the value Nack once the _WTRU notices that the previous acknowledgement transmission was successful. For example, the WTRU may set

,in

Can be the number of previously successfully transmitted acknowledgments.

As described herein, in NR-U transmissions, the WTRU or gNB may continue to transmit in the unlicensed channel for a maximum duration after performing a successful LBT procedure. In some cases it is necessary to share the COT. When a device such as a WTRU or gNB starts a COT in an unlicensed channel, it is also possible to share the COT with another device (eg, a gNB or WTRU, respectively) that transmits during the COT. For example, if the gNB starts and "owns" the COT (ie, the COT owned by the gNB), it may share the COT with one or more WTRUs, or if the WTRU starts and "owns" the COT (ie, the COT owned by the WTRU), it may Share COT with its gNB. for better in unauthorized channel Coexistence and more efficient transmission and reception, COT sharing can be limited by some rules. The use of COT sharing in NR-U enables better coexistence in unlicensed channels and more efficient transmission and reception.

In a configured grant (CG) or grant-free transmission, the WTRU may execute LBT procedures (eg, LBT CAT-3 or CAT-4), where the LBT procedures are associated with a priority level, and establish a COT. The WTRU may transmit its pending TB or TBs to its gNB using the CG transmission rules. The WTRU may then share its COT (WTRU's WTRU-owned COT) with the gNB. The gNB may use this shared COT for some purposes. For example, the gNB may send a CG-DFI to the WTRU that carries HARQ feedback for one or more TB transmissions immediately preceding, or one or more TB transmissions prior to establishing the COT. The gNB may also transmit one or more TBs to the same WTRU or one or more other WTRUs.

For more efficient COT sharing, the WTRU may indicate the properties of the COT to the gNB. These attributes may be sent by the WTRU to the gNB in the last or some of the last CG PUCCH transmissions, and these attributes may be carried in the CG-UCI. COT attributes carried in the CG-UCI may include the following: duration of the COT (eg, duration interruption, eg, total duration, duration expected to be used by the WTRU owning the COT, and/or the rest of the COT); establishment The access class (AC) or access priority level for which the COT is intended; whether the gNB is allowed to use the COT for DL transmissions to other WTRUs; and/or whether the gNB is allowed to use the COT to schedule UL transmissions to other WTRUs.

When the gNB begins transmission in the COT shared by the WTRUs, the gNB may advertise the COT attributes to other WTRUs. The COT attribute (common to WTRUs) may be part of the COT attribute sent by the gNB at the beginning of the COT and/or retransmitted at the beginning of subsequent slots of the COT. The gNB may send COT attributes at the beginning of the COT or at the beginning of a common transmission.

COT sharing may be performed between two or more WTRUs (eg, two WTRUs participating in CG transmissions to their gNBs). For example, WTRU1 may start the COT and transmit its pending TB or TBs in the CG PUSCH. WTRU2 may then use the same COT to transmit its own CG PUSCH. However, WTRU2 may need to be notified of the COT owned by WTRU1. In one approach, WTRU1 may send its COT attributes to the gNB, which indicates that other WTRUs may use the rest of the COT. The gNB then advertises the COT attribute to other WTRUs in the Group Common (GC) PDCCH.

The COT established by the WTRU may be for CG or spontaneous uplink (AUL) transmissions. When this COT is shared with the gNB, a shared COT can be used between the CG (or AUL) and scheduled or grant-based UL transmissions. For example, the gNB may use the COT owned by WTRUl to schedule grant-based (or scheduled UL) for WTRU2. However, for this, the gNB may need to know that WTRU2 has one or more TBs pending for transmission. In some cases, the gNB may have received the WTRU's scheduling request (SR) in the previous or immediately preceding COT, and/or have no time or scheduling resources to schedule UL transmissions for the WTRU in the COT . Alternatively, the gNB may schedule SR resources for all WTRUs in the first or previous time slots after the gNB starts using the common COT, where the SR resources may be used to indicate to the gNB that it has one or more TBs pending. After receiving the SR from the WTRU, the gNB may schedule the UL in the remainder of the shared COT owned by shared WTRUl.

When a WTRU is to share its owned COT with its gNB, the WTRU may perform one or more actions to ensure that the gNB can begin its downlink transmission within a gap defined by the regulatory rules (eg, the gap may be 25 μs in duration). If the gNB starts transmission within this gap, COT sharing can be performed within the regulatory rules. Otherwise, if the gNB cannot start transmitting within the duration of the gap, the gNB may have to go through a full LBT procedure (CAT3 or CAT4) before being able to transmit. for The WTRU may perform one or more of these actions in order to increase the chances that the gNB will successfully use the common COT owned by the WTRU.

One such action may be for the WTRU to extend the Cyclic Prefix (CP) of one or some of the last symbols to align within the policing duration (eg, 25 μs) before the start of the next slot or the start of the next opportunity where the gNB can start the micro slot. the end of its transmission. Note that the WTRU may indicate this CP extension to the gNB in advance, eg, in the CG-UCI.

One such action may be for the WTRU to transmit a sounding reference signal in the last symbol or symbols of a time slot within the supervised duration (eg 25 μs) before the start of the next time slot or before the start of the next opportunity where the gNB can start a mini-slot (SRS).

In the COT attributes, some measurements from WTRUs that have acquired COT may also be reported (eg, RSSI, Reference Signal Received Power (RSRP), etc.). COT sharing may be prioritized between sets of WTRUs and gNBs, where one device acts as a primary (or master) node and the other device is a secondary (or slave) node between them.

Figure 12 is an exemplary transmission diagram for base COT sharing. In general, base COT sharing may be used in scenarios where the WTRU has a low traffic load or in lower density situations where the hidden node problem is less pronounced. In Figure 12, each square may represent one or more time slots. The COT duration 1220 may include the WTRU1 COT 1222 and the COT common portion 1224. Initially at 1201, the WTRU may acquire COT by performing LBT (eg, for transmission in preconfigured CG/license-free resources). On the first transmission after acquisition, the WTRU may transmit the COT attributes and other attributes related to the WTRU CG transmission to the gNB (at 1202). These attributes may be carried on UCI multiplexed on PUSCH. Once the PUSCH transmission is complete, at 1203, the gNB may take over the COT (ie share the COT), where one or more of the following may occur: The gNB advertises the COT in the GC-PDCCH attributes (also at 1203); at 1204 the gNB transmits the PDCCH with the WTRU allocation; at 1205 the gNB/WTRU transmits the PDSCH/PUSCH based on the PDCCH allocation; and/or at 1206 the gNB/WTRU transmits based on the received PDSCH/PUSCH PUCCH/PDSCH (ie for ACK).

Alternatively, the COT sharing procedure may include other steps to limit the influence of hidden nodes. Figure 13 is an exemplary transmission diagram for COT sharing limiting the influence of hidden nodes. The COT duration 1320 may include the WTRU1 COT 1322 and the COT common portion 1324. Initially, at 1301, the WTRU may acquire the COT based on the LBT (eg, to transmit in a pre-configured CG/license-free resource). At 1302, on a first transmission after acquisition, the WTRU may transmit the COT attribute to the gNB. These COT attributes may be carried by short transport blocks that cause UCI to be multiplexed on PUSCH, by short PUCCH, or by modified SR using UCI on PUCCH. Upon receipt of the WTRU COT attributes at the gNB, the gNB may transmit the common COT attributes (at 1303), where these attributes may be the exact COT attributes requested by the WTRU, or may be a modified set of COT attributes requested by the WTRU, including the WTRU reserved attributes and other common COT attributes. At 1304, the WTRU may then transmit its desired data to the gNB in the PUSCH. When the PUSCH transmission is complete, the gNB may take over the COT, where the gNB may transmit the PDCCH with the WTRU assignment (1305), the gNB/WTRU may transmit the PDSCH/PUSCH based on the PDCCH assignment (1306), and/or the gNB/WTRU may transmit the PDSCH based on the received PDSCH /PUSCH to transmit PUCCH/PDSCH (for ACK).

Although features and elements are described above in specific combinations, one of ordinary skill in the art would understand that each feature or element can be used alone or in any combination with other features and elements. Furthermore, the methods described herein can be implemented in computer programs, software and/or firmware incorporated in a computer-readable medium for execution by a computer and/or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer-readable storage media. computer Examples of readable storage media include, but are not limited to, read only memory (ROM), random access memory (RAM), scratchpad memory, cache memory, semiconductor memory devices, magnetic media (eg, internal hard drives and removable disks), magneto-optical media, and optical media such as CD-ROMs and/or Digital Versatile Discs (DVDs). The processor associated with the software may be used to implement a radio frequency transceiver for the WTRU, UE, terminal, base station, RNC, and/or any host computer.

801: Time

810, 820: Channel Occupancy Time (COT)

DAI: Downlink Assignment Indicator

EDAI: Enhanced Downlink Assignment Indicator

LBT: first listen and wait

PDCCH: Entity Downlink Control Channel

PDSCH: Entity downlink shared channel

PUCCH: Physical Uplink Control Channel

Claims (14)

A method performed by a wireless transmit receive unit (WTRU), the method comprising: receiving a first control for a first physical downlink shared channel (PDSCH) transmission on a first physical downlink control channel (PDCCH) information, and wherein the first control information further includes a first HARQ feedback timing indicator; based on a value of the first HARQ feedback timing indicator, determining not to send a first HARQ feedback for the first PDSCH transmission; at Receive a second control information for a second PDSCH transmission on a second PDCCH; and send a HARQ feedback based on the second control information, the HARQ feedback including combining with a second HARQ feedback for the second PDSCH transmission the first HARQ feedback for the first PDSCH transmission. The method of claim 1, wherein the second control information includes a second HARQ feedback timing indicator. The method of claim 1, wherein the HARQ feedback for the first and second PDSCH transmissions is sent based on a timing indicated by a second HARQ feedback timing indicator. The method of claim 1, wherein the HARQ feedback for the first and second PDSCH transmissions is sent on a physical uplink control channel (PUCCH) resource indicated in the second control information. The method of claim 1, wherein the first HARQ callback timing indicator is a first PDSCH-to-HARQ timing indicator, and a second HARQ feedback timing indicator is a second PDSCH-to-HARQ timing indicator indicator. The method of claim 1, wherein the second control information includes an indication of a PDSCH transmission group to include in the HARQ feedback, wherein the PDSCH transmission group includes the first PDSCH transmission and the first PDSCH transmission Two PDSCH transmissions. The method as described in claim 1, further comprising performing a listen-to-wait (LBT) before sending the HARQ feedback. A wireless transmit receive unit (WTRU) comprising: a processor operatively coupled to a transceiver; the transceiver configured to receive messages directed to a first entity on a first entity downlink control channel (PDCCH) a first control information for downlink shared channel (PDSCH) transmission, and wherein the first control information further includes a first HARQ feedback timing indicator; the processor is configured to be based on a first HARQ feedback timing indicator value to determine not to send a first HARQ feedback for the first PDSCH transmission; the transceiver is configured to receive a second control information for a second PDSCH transmission on a second PDCCH; and the transceiver is configured to: send a HARQ feedback based on the second control information, the HARQ feedback including the first HARQ feedback for the first PDSCH transmission combined with a second HARQ feedback for the second PDSCH transmission. The wireless transmit receive unit (WTRU) of claim 8, wherein the second control information includes a second HARQ feedback timing indicator. The wireless transmit receive unit (WTRU) of claim 8, wherein the HARQ feedback for the first and second PDSCH transmissions is sent based on a timing indicated by a second HARQ feedback timing indicator. The wireless transmit receive unit (WTRU) of claim 8, wherein the HARQ feedback for the first and second PDSCH transmissions is a physical uplink control channel (PUCCH) indicated in the second control information ) resource is sent. The wireless transmit receive unit (WTRU) of claim 8, wherein the first HARQ feedback timing indicator is a first PDSCH to HARQ timing indicator, and a second HARQ feedback timing indicator is a first HARQ feedback timing indicator Two PDSCH to HARQ timing indicators. The wireless transmit receive unit (WTRU) of claim 8, wherein the second control information includes an indication of a PDSCH transmission group to include in the HARQ feedback, wherein the PDSCH transmission group includes the first A PDSCH transmission and the second PDSCH transmission. The wireless transmit receive unit (WTRU) of claim 8, wherein the processor and the transceiver are configured to perform a listen before sending (LBT) before sending the HARQ feedback.

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